The present invention relates to an induction heating apparatus which may be used as a cooking device.
The induction heating apparatus generally comprises a static power converter for converting low-frequency power into high-frequency power and at least one heater coil which is arranged to be energized by the high-frequency power. When the induction heating apparatus is used as a cooking device and is subjected to a load such as a cooking pan placed in the vicinity of the heater coil, the impedance of the circuit including the heater coil varies in a broad range in dependence upon the material forming the load. This results in serious fluctuations in the operating conditions of the heater coil and the converter. The fluctuations in the operating conditions of the power converter and the heater coil are, furthermore, caused by an unusual change in the current or the voltage applied to the heater coil and, in the result, tend to invite an over-current through the heater coil and burn-out of the heater coil and destroy insulating materials incorporated into the heating unit.